Apoptotic-like nuclear morphology and mitochondrial damage in lymphocytes of an HIV-infected lymph node. (A) One normal lymphocyte and one lymphocyte with initial chromatin condensation and mitochondrial swelling (arrow) in a cell suspension obtained from the lymph node (original magnification [OM] × 9,000). (B) A tissue section from the same lymph node showing one cell with similar nuclear and mitochondrial abnormalities and partial fusion of nuclear and plasma membranes (arrow) (OM × 8,000). (C) A tissue section showing two cells in which the chromatin has collapsed down along the nuclear envelope. One of the cells (arrow) is engulfed by a macrophage and presents swollen and tightly packed mitochondria; the other cell (arrowhead) is free, and presents condensation of nucleolus and extreme reduction of cytoplasm with loss of intercellular contacts (OM × 4,900). (D) A tissue section showing several cells with initial chromatin condensation (arrows) and one cell with normal nuclear morphology (arrowhead), all displaying mitochondrial swelling (OM × 3,300). Note in all micrographs the intact mitochondria of neighboring cells.